Alkylated aromatic hydrocarbons



Sept. 4, 1945. RJ. GAYLOR ALKYLATED AROMATIC/ HYDROCARBONS Filed June 19, 194;

atented Sept.v 4, 1.945

v 2,384,295 i spamrun AnoMA'rrc mnooAnoNs" Peter J. Gaylor, Union, N. J., assigner to Stan `*Oil Development Company, a corpus-anon ot Delaware Application June 19, 1941, S l it?.

1o claims. (ci. esca-cri) The present invention is concerned with an improved process for the preparation of alkylated aromatic hydrocarbons, and particularly ethyl benzene. The invention is more particularly concerned with a process for the treatment of commercial or impure benzene by which it is -possible to subsequently react the same with ethylene i under conditions in which substantially improved catalyst. l

1t is well known in the art to produce ethyl benzene by various operations. For example, one

conventional process employed is to condense ethylene with .benzene in the presence of aluminum chloride or other similar catalyst, followed by removing the ethyl benzene by a distillation process. Anoperation of this character, while entirely satisfactory for producing the ethyl benzene, does have the disadvantage that relatively low yields of ethyl benzene are secured per unit volume of catalyst employed, particul .ely when the benzene is secured from commercial sources.

I have, however, now discovered that, providing the feed 4benzene be treated in an initial stage with a relatively small quantity of aluminum chloride and the sludge removed, followed loy reacting the benzene in a. secondary stage with ethylene and additional catalyst, a marked unexpected improvement in yield is secured. 'l'.l'iel process of my invention may be readily understood by reference to the attached drawing illustrating one embodiment of the same. For the purpose of description it is assumed that the benzene comprises one secured from coal tar. This benzene is introduced into the system by means of line i. The benzene is mixed with asuitable catalyst which for the purpose of description is taken to be aluminum chloride, which is introduced into line l by means of line 2, passed through mixer 3, heating zone d and then introduced `into separation zone a. Temperature and pressure conditions are adjusted'so as to secure the formation of a sludge which is removed by means of line 6 along with the added aluminum chloride. The pretreated benzene is withdrawn from separation zone 6 by means of line l and combined with ethylene means of line t.

Additional aluminum chloride is introduced into the system 4by means oi line Q, the mixture passed through mixing zone l0, heating Zone il, and introduced into vseparation zone it. The spent aluminum chloride is removed by means of line it while the reaction product comprising ethyl benzene is removed by means of line la and passed into distillation zone le wherein the unreacted ethylene is removed overhead by means of line l5 and returned to ethylene storage li from where it may he recycled to the system by means of line The unreacted benzene is removed as an intermediate side stream by means of line l@ `and preferably recycled to the secondary stage. However, under certain condi,- tions it may be desirable to withdraw this benzene from the system by means of line i9. The ethyl benzene is removed from distillation zone la by means of line 2c.

The process of the present invention may be widely varied. The invention essentially come prises pretreating benzene ln an initial zone with a catalyst, preferably with a small amount of aluminum chloride in order to remove objectionable constituents, followed by contacting the treated benzene in a secondary stage with additional catalyst, preferably aluminum chloride in the presence of ethylene, under conditions to form ethyl benzene. It is to be understood that the respective zones comprise any suitable numn bei and arrangementof units.

which is introduced by The catalyst employed in the initial zone may comprise any suitable material which will tend -to form a sludge of the objectionable constituents. Suitable catalysts are Friedel-Claim type halides or mixtures thereof. However, the preferred substance comprises aluminum chloride. The amount of aluminum chloride employed may vary considerably depending upon the character oi' the benzene and the related operating conditions. However. in general I prefer to employ from 0.01 to 0.1 mol of aluminum chloride per mol of benzene. In accordance with the preferred modiication of my invention, it is desirable to employ atmospheric pressure although higher pressures may be used if desiredin the initial stage, and to contact the aluminum chloride and benzene at a temperature in the range from about to 200 F., preferably 140 to F. The benzene and aluminum chloride are held at this temperature for a sufficient time period which` is in the range from about 1/2 'to 2 hours.

The treated benzene removed from the initial stage is then contacted with a catalyst adapted to secure the ethylation of the benzene. Although catalysts such as Friedel-Crafts halides may be used. I prefer to employ aluminum chloride. In general, it is desirable to use from 0.5 to 1.5 mols of aluminum chloride per 6 to 10 mols of benzene. The ethylation reaction is generally conducted by employing approximately 3 mols of benzene per mol ofethylene. The temperature is conducted in the general range from about 130 to 180 F. and at atmospheric pressure, although higher pressures may be employed. The time of reaction will vary widely depending upon speciiic operating conditions but in general is about V2 to 11/2 hours.

Under these conditions, the amount of ethylbenzene formed per'unit volume of catalyst is appreclably high.

In order to illustrate the invention further, the following example is given which should not be construed as limiting the same in any manner whatsoever:

Example 1 commercial benzene obtained from coal tar was reiluxed with 0.01 mol fresh AlCls per mol of benzene for one hour was settled and the thus treated benzene was alkylated with ethylene (3 mols benzene per mol ethylene) with a contact time of about one hour at 160 F. to obtain a yield of 16.7 lbs. of ethyl benzene per pound pf catalyst. This compares with a yield of 10.7 lbs. with commercial untreated benzene, and 15.4 lbs. with a commercially puried benzene.

Example `Z.

In one operation. commercial benzene was treated with 5 pounds of 98% sulfuric acid per barrel. The benzene was then treated with caus. tic, followed by washing with water and then drying. The acid treating about 1 The benzene was then ethylated, employing an aluminum chloride catalyst at a temperature of about 160 F. and atmospheric pressure. Under these conditions, the yield of ethyl benzene was 10.7 lbs. per pound of aluminum chloride.

In another operation, the commercial benzene was employed directly for the ethylation of benzene under identical conditions using aluminum chloride as the catalyst.

In a third operation, the commercial benzene was treated under the same conditions in an initial stage with spent aluminum chloride catalyst'secured from the secondary stage of the alkylation reaction.

, The results of the respective operations were/ as follows:

Yield using operation From the above.' it is apparent that unex`- pected high yields are secured in accordance with the present process.

This invention, although especially valuable in the preparation of ethyl benzene is also applicable to the alkylation of other aromatics with loss was less thannaphthalene, anthracene,

at 160 F. The mixture v ride catalyst already used other oleiins, e. g. propylene, butylene, etc. with etc.

What I claim as new and wish to protect by Letters Patent is:

1. Process for obtaining improved yields of alkylated aromatic hydrocarbons from oleiins and impure aromatic hydrocarbons comprising treating said aromatic hydrocarbons with about 0.01 to 0.1 mol of a Friedel-Crafts catalyst per mol of aromatic hydrocarbon separating the treated aromatic hydrocarbons from the resulting catalyst sludge. and then aklylating the thus treated aromatic hydrocarbons with an olen inI the presence of a Friedel-Crafts type catalyst.

2. Process for obtaining improved yields of ethyl benzene from benzene of commercial purity, comprising treating said benzene with about 0.01 to 0.1 moi of aluminum chloride per mol of benzene separating the treated benzene from the resulting aluminum chloride sludge and then alkylating the thus treated benzene with ethylene in the presence of ay Friedel-Crafts type catalyst.

3. Process according to claim 2 in lwhich the benzene is a coal tar derivative.

4. Process according to claim 2 in which the treatment prior to alkylation is conducted at ap proximately 120 to 180 F. i

5. Process according to claim 2 in which the treatment prior to alkylation is conducted for a time of about 1/2 to 1% hours.

6. Process for obtaining improved yields oi alkylated aromatic hydrocarbons from oleflns and impure aromatic hydrocarbons comprising treating said aromatic hydrocarbons 'with a spent aluminum chloride catalyst already used in an alkylation reaction, separating the treated aromatic hydrocarbons from the resulting aluminum chloride sludge, then alkylating the separated aromatic hydrocarbons fwith an olefin in the presence of fresh aluminum chloride catalyst.

'7. Process for obtaining improved yields of ethyl benzene by alkylating benzene with ethylene in the presence of an aluminum chloride alkylation catalyst comprising treating benzene of commercial purity with a spent aluminum chloin an alkylation reaction, separating the treated benzene from the resulting aluminum chloride sludge, then alkylating said separated benzene with ethylene in the presence od fresh aluminum chloride.

8. Process for obtaining improved yields of alkylated aromatic hydrocarbon from an olefin and an impure aromatic hydrocarbon comprising treating said aromatic hydrocarbon with about 0.01 to 0.1 mol of aluminum chloride per mol of aromatic hydrocarbon, separating the resulting aluminum chloride sludge from the treated aromatic hydrocarbon, then passing the treated aromatic hydrocarbon in a mixture :with an olefin and fresh aluminum chloride through an alkylation zonel in which said aromatic hydrocarbon is maintained in a proportion substantially in excess of alkylation requirements, separating aluminum v'chloride sludge from the alkylation products, separately withdrawing alkyllated aromatic hydrocarbon product and returning unalkylated aromaticv hydrocahbon to said alkylation zone.

9. Process for obtaining improved yields of ethyl benzene comprising treating benzene o! commercial purity with about 0.01 to 0.1 mol of aluminum chloride per mol of benzene. separating the resulting aluminum chloride sludge from the treated benzene and passing the latter in admixture with ethylene and fresh aluminum 10. Process according to claim 9 in which the said aluminum chloride used in the said iirst mentioned treatment of benzene olf commercial purity is spent aluminum chloride withdrawn 5 from the said alkyiation products.

PETER J GAYLOR. 

